An object of the present invention is to provide a light diffusion sheet having a favorable cost reduction capability due to excellent scratching preventive property of the front face, and having in addition thereto, a favorable directional light diffusion function, transmittivity of rays of light, and a thin film character; and a backlight unit capable of promoting performances such as luminance as well as price reduction, and thin and light modeling capability. The light diffusion sheet of the present invention has a light diffusion sheet including a transparent substrate layer, and a light diffusion layer overlaid on the front face side of the substrate layer, wherein the light diffusion layer has resin beads and a resin binder, characterized in that the light diffusion layer has protruding parts having a shape of a partial spherical body on the front face in a scattering manner. It is preferred that mean height of the protruding parts be 1 μm or greater and 10 μm or less, mean diameter of the protruding parts be 4 μm or greater and 18 μm or less, mean occupancy rate of the protruding parts be 2% or greater and 20% or less, and surface roughness (Ra) of the light diffusion layer be 1.5 μm or greater and 10 μm or less. As the beads, small monodisperse beads as a principal component, and large beads as a sub component may be included.